#include <search.h>
#include "tsearch.h"

static void walk(const struct node *r, void (*action)(const void *, VISIT, int), int d)
{
    if (!r)
        return;
    if (r->h == 1)
        action(r, leaf, d);
    else {
        action(r, preorder, d);
        walk(r->a[0], action, d+1);
        action(r, postorder, d);
        walk(r->a[1], action, d+1);
        action(r, endorder, d);
    }
}

void twalk(const void *root, void (*action)(const void *, VISIT, int))
{
    walk(root, action, 0);
}
